Additional evidence for the role of viruses and/or genetics in the etiology of cancer was provided in several studies. Analysis of data including HTLV-I antibody titers on serum samples from more than 42,000 individuals in various geographic locales suggested that in addition to Japan and the Caribbean Islands, HTLV-I or a closely related virus was endemic in Panama, New Guinea and sub-Saharan Africa. Newly identified populations with antibodies reacting against HTLV-I antigens included Indians living in Florida and Panama. The detection of a native born Panamanian Mestizo with HTLV-I-associated adult T-cell leukemia/lymphoma extended our knowledge of people at risk for this disease. The etiologic role of the Epstein-Barr virus (EBV) in nasopharyngeal carcinoma was strengthened by the detection of EBV in biopsies from all American patients entered into a multicenter collaborative study, including all with the more differentiated form (WHO type I) of NPC which had been thought by many not to be EBV-associated. A study of several populations for antibodies to a newly isolated virus (human B- lymphotropic virus of HBLV) from the Laboratory of Tumor Cell Biology, NCI extended our knowledge about its prevalence in the general population and association with several diseases. Specific findings involving the role of genetics in the etiology of human cancer included: 1) the first report on familial breast cancer in black Americans, 2) the evaluation of a white family with an increased incidence of cancer which included three siblings with NPC, and 3) the identification of a monocyte deficiency in a family with a high frequency of immunologic and hematologic (including acute myelomonocytic leukemia) abnormalities that may be a previously undescribed entity similar to, but distinguishable from, Fanconi's anemia.